Answer:
waves that move through matter only are called mechanical waves.
waves that move through space only are called electromagnetic waves.
A curved line or surface cannot be measured by a straight scale, a measuring tape or thread must be used instead.To measure a curved line using a thread, follow the below steps:
Tie a knot at one end of the thread.
Place the thread at the beginning of the line and try to measure a small initial portion of the line which is relatively straight.
Place your thumb at the other end of the measured portion and measure next straighter portion.
Repeat the above step till the end of line is reached. Make a knot at the end of the line.
Now, straighten the thread and measure the length of the two knots on a scale.
The answer should be compound
Answer : Nuclear fusion plays an important role in making elements that are heavier than helium.
Explanation : In the given attachment it is clearly observed that nuclear fusion reactions are playing a vital role in making the small elements fuse together to form a higher element as a product. This is observed in those elements which are heavier than helium. The atoms of the elements fuse together and make a larger atomic molecule which is the sum of both the elemental masses.